Lamellar ichthyosis (IL) is a rare autosomal recessive genodermatosis with a defect of keratinization of the skin which results in a severe generalized cutaneous xerosis with dark brown big scales, an ectropion, an eclabion, an alopecia and a palmo-plantar keratodermia. They are due to mutations of the gene TGM1 coding for the transglutaminase keratinocyte 1 (TG1) in 1/3 of the cases. Other genes were recently identified, ABCA12 coding for the triphosphate-binding adenosine cassette A12 and FLJ39501 which codes for a protein of the cytochrome p450 ( CYP4F2).